Google Books definitely treads on dangerous ground when it comes to copyright issues. Here's just one question that any settlement is unlikely to decide: What gives a U.S. court the right to speak for millions of rights holders who don't know or care about Google Books? But for many opponents, copyright infringement is just one troubling aspect of the project.

Other opponents are more worried about privacy issues. For example, in spite of Google Books' privacy policy, it's possible that Google could track what you read, right down to specific pages, with dates and times included.

Because Google is a for-profit organization, it only made sense to generate revenue from its ever-growing index of books and the associated tracking data garnered from users. As Google displayed snippets from public domain and copyrighted books, it also shows adjacent advertisements related to the book and its subject, offering to sell you products with related content. This kind of targeted marketing is a sure revenue generator. If Google can exploit that kind of detailed data for commercial gain, it could use it for more nefarious purposes, too.

Profit issues are at stake, too. Authors and publishers witnessed Google displaying their work and profiting from their texts, so they fought back with a lawsuit. They claimed Google was clearly committing copyright infringement on an incredible scale, and in the process, profiting from its actions. And although Google didn't show the entire contents of copyrighted books, what would stop the company from doing so at a later date?

On a technical and philosophical level, who would stop Google from censoring parts of books, or from eliminating whole texts? And because the legal settlement lets authors and publishers to opt out of the Book Rights Registry database, there's a potential for a form of self-censorship on the part of rights holders, too.

And what if a growing dependence on Google Books' authority actually caused an information gap? Once people began assuming that Google had scanned every book, it seems logical that they'd also assume that if the information wasn't on Google Books, it simply didn't exist.

What's more, what if Google Books constitutes a monopoly? With Google as the digital hub of the world's books, the company would control access to knowledge. Then Google could potentially charge immense fees to the organizations who wanted to tap into the Google Books database.